Parameterisation of surface radiation flux at an Antarctic site (original) (raw)
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2005
The analysis of measurements of daily mean temperature, daily mean relative humidity and daily total solar irradiation for the period 1979-1985, at the Antarctic stations Almirante Brown (64.9oS, 62.9oW, 10m a.s.l., West of Antarctic Peninsula), and BelgranoII (77.9oS, 34.6oW, 250m a.s.l., East of Antarctic Peninsula) is presented. A short-term characterization of monthly averages was established. Typical temperatures for summer and winter were 2oC and –7oC respectively at Brown, and –2oC and –20oC at BelgranoII. Relative humidity was always above 60% at both stations. Both measured parameters enter also as input variables in model calculations of the equivalent clear-sky daily total irradiation for each day, to determine the effective cloud transmittance of solar radiation. The effect of cloudiness was stronger at Brown, where an average cloud transmittance of 49% was determined, while it was of 71% at BelgranoII. Average daily irradiation of 27.4MJ/m 2 in December at BelgranoII is...
Effects of Drifting Snow on Surface Radiation Budget in the Katabatic Wind Zone, Antarctica
Annals of Glaciology, 1985
Effects of drifting snow are examined from measurements of radiation fluxes at Mizuho Station in the katabatic wind zone, Antarctica. A good correlation is found between the difference of downward longwave fluxes measured at two heights and wind speed used as an index of drifting snow. The wind increases the downward flux at a rate of 2 W m-2/m s-2when wind speed is higher than 13 m/s. Drifting snow suppresses the net longwave cooling at the surface. Direct solar radiation is depleted greatly by the drifting snow; however, the global flux decreases only slightly, compensated by the large increase of the diffuse flux, at a rate of about 1% for each 1 m/s increase in wind speed. At Mizuho Station, the effect on longwave radiation prevails throughout the year. The relation between snow drift content and wind speed is obtained from shortwave optical depth measurements as a function of wind speed. A simple parameterization of radiative properties is given.
Radiative effects of clouds, ice sheet and sea ice in the Antarctic
The effects of clouds, ice sheet and sea ice on the radiation budget in the Antarctic were examined using the ERBE data and surface observations at Antarctic stations in 1987/1988. Long-wave radiation emitted by clouds was found to heat the surface throughout the year and strongly cool the atmosphere over Antarctica. The elevation of the ice sheet surface reduced the outgoing long-wave radiation, making the radiation budget in the two polar regions asymmetric. Sea ice had a significant impact on radiation; however, cloud distribution reduced the effect.
2021
We have characterized the snow albedo decay over Hurd Peninsula, Livingston Island, Antarctica, for the period 2000–2016. The snow albedo was obtained from the MOD10A1 product of the spaceborne MODIS sensor. A low-pass filter is applied to the data in order to eliminate short-term variations and retain the seasonal variation of albedo. The seasonal albedo was fitted to an exponential decay function to obtain the decay rate, the duration and the starting date of the decay. On average, albedo decay starts in late September and lasts for 96 ± 20 days. Snow melting lags behind snow albedo decay. This lag is due, on the one hand, to the occurrence of dry-snow metamorphism and sublimation in the early stages of the decay, and on the other hand to persisting subsurface melting after the completion of the metamorphic processes at the surface. The albedo decay is mainly driven by the shortwave incident radiation, with air and near-surface temperatures unexpectedly playing a minor role. Near-...
Radiative Transfer Model We present results from a 3-D radiative transfer simulation o f The SAMCRT code treats surface-radiation processes in fine the radiation environment of Palmer Station, Antarctica. Th e detail, at the expense of somewhat simplified atmospheric model results for several wavelength bands in the SW indicate treatment, at least as compared with state-of-the-ar t that plane-parallel models of either top of the atmospher e atmospheric Monte Carlo RT models. The main physical (TOA) radiance or surface irradiance may produce significan t mechanisms treated by SAMCRT are described below. errors when applied to regions of high surface albed o heterogeneity. Since high-latitude clouds tend to show little vertica l